UK CBAM record-keeping starts before you register

The UK CBAM record duty starts on 1 January 2027 and applies whether or not you register. SI 2026/802 turns several core record, registration and return requirements into final rules. The central record duty is not limited to registered persons.

Many UK importers treat CBAM as a problem that begins at registration. If they expect to stay below the registration trigger, they assume there is nothing to build yet. That assumption is wrong.

The record duty starts before registration does

If you import a CBAM good in the course of a business, you must record five fields. They are the commodity code at the 8-digit level, the description, the import date, the value and the weight.

This duty applies whether or not you are registered. It covers an importer below the registration trigger, and an importer who has not yet reached the point where registration becomes necessary.

Two of those fields have a prescribed measure. The basic weight measure is net of packing, measured at UK import and expressed in kilograms. Value follows the applicable UK customs-valuation route.

Retention rules fall into two groups. You must generally keep records linked to an accounting periodaccounting periodThe period for which a UK CBAM return and payment are calculated. for 6 years from the day after that period ends. You must keep other covered records for 6 years from creation. All of them must be in writing.

Registration data and return data are not the same set

The registration dataset is the broader of the two. It covers identity and contact details, business form, EORI, any VAT number held, the trigger date and import-value information for the applicable test.

It also requires an estimate of import weight by CBAM sector over the following 12 months. You must retain the evidence that supports the information you supply.

The instrument specifies narrower return fields. For each charged CBAM good, the return requires the 8-digit commodity code, the weight, the carbon-price-relief amount and the place of origin. The return must also carry a declaration that it is true and accurate to the maker's best knowledge.

As made, the instrument did not make emissions intensity, actual-versus-default status or precursorPrecursorUpstream CBAM good consumed as input to a complex-good process; listed per route; quantities always monitored per Annex II pt E. data part of that core return list. SI 2026/995 has since amended it. The return now also carries the default-value level and the verified emissions intensity, and you must evidence both for 6 years.

HMRC can still require additional information by notice. That notice power is the route by which further fields can arrive.

If the weight record is wrong, an officer can set it

Origin follows the non-preferential customs-tariff rules identified in the instrument. You must retain the supporting origin evidence.

Weight carries a sharper consequence. If the recorded weight is wrong, or the required weight record is missing, an HMRC officer may determine the weight.

The officer may work from estimates, assumptions, comparisons, inspection material or other evidence, and must notify the person in writing. In practice, someone other than you can set the weight used against you.

Reimbursement: 90 days, no fee, no deduction

The regulations also prescribe conditions for reimbursement arrangements. Reimbursement must be completed within 90 days, without a fee or deduction, and in the manner prescribed by HMRC.

If the sum is not reimbursed, it and the related interest must be repaid to HMRC. That repayment falls due 14 days after the end of the 90-day period.

What it means for importers

Your record-keeping obligation begins with your first business import of a CBAM good, not with registration. Gaps in weight records carry the sharpest risk, because an officer can then set the weight for you.

What to do

• Run the import-data gap check this week. Open your customs data for every business import that could be in scope. Confirm that it holds an 8-digit code, a description, an import date, a customs valuecustoms valueThe value determined under customs valuation rules, normally starting with transaction value and prescribed adjustments., a net weight and origin evidence.
• Keep two evidence files, not one. Registration evidence and return evidence are not identical datasets, and merging them makes it harder to show which record supported which submission.
• Assign one named owner to monitor HMRC notices before you prepare any live registration or return.
• Add the default-value level and the verified emissions intensity to your return checklist, because SI 2026/995 now requires them. Mark any other expected field as pending until the legislation or notice that requires it is published.

Stuck on this in your own import data? Write to us and we will look at it with you.

This article explains the as-made text of SI 2026/802 and its later amendment. Recheck both instruments, and any HMRC notices issued under them, immediately before operational use. It is not legal, tax or customs advice.